Paul Miller, MD, Medical Director, Colorado Center for Bone Research, Boulder, Colorado, United States, and colleagues analyzed the relationship between teriparatide-related increases in lumbar spine BMD and the risk of new vertebral fractures.

The researchers looking at data from the Fracture Prevention Trial, a randomized, double-blinded trial that evaluated teriparatide (Forteo) and enrolled 1637 women with osteoporosis.

Teriparatide is supplied in a disposable pen device that can be used for up to 28 days to give once-daily self-administered injections. Subjects were randomized to teriparatide 20 mcg/day, teriparatide 40 mcg/day or placebo for a median of 19 months.

For their study, Dr. Miller and his team assessed lumbar spine BMD at baseline and after 18 months. Baseline and endpoint lateral spine x-rays were assessed using a visual semiquantitative technique to determine changes in fracture status. They used logistic regression analysis to model vertebral fracture risk as a function of therapy (placebo or pooled teriparatide), endpoint lumbar spine BMD at 18 months and interaction with therapy.

Results show that both baseline BMD and changes in BMD were contributors to the prediction of fracture risk. The average increase in BMD for teriparatide-treated patients was 0.09 g/cm². This increase was similar across baseline BMD values.

Teriparatide-related increases in BMD accounted for 30% to 41% of vertebral fracture risk reduction; the remainder of the risk reduction was due to improvements in other non-BMD determinants of bone strength.

"While BMD remains the most useful diagnostic tool for identifying patients with osteoporosis and is often used to measure the efficacy of osteoporosis therapy, the ultimate goal for any osteoporosis therapy is to reduce fracture risk," said lead author Dr. Paul Miller MD, Medical Director of the Colorado Center for Bone Research.

"This study gives us an indication that BMD gains do not equal proportional fracture risk reduction," he concluded.

Dr. Miller said additional research is needed to identify what those other factors are.


[Presentation title: Change in Bone Mineral Density (BMD) and Fracture Risk Reduction in Teriparatide-Treated Women with Osteoporosis. Abstract 1223]

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